Create an offline layer

In this topic

Taking individual layers offline allows you to build apps that can operate without network connectivity. Your users will be able to continue viewing maps, getting directions to locations, query and identify features, edit data and synchronize it when connectivity returns. You can choose to
take a whole map and all of its layers offline but taking individual layers offline gives you more granular control. For example, you can decide when and how individual offline layers are created, used, and synchronized within your app.

Use either the Services pattern or the Desktop pattern to take layers offline. With the
Services pattern you can use this API to download tile and feature data to your device from any ArcGIS Online or ArcGIS Enterprise service (as long as the service is enabled for offline use). With the
Desktop pattern you can author packages in ArcGIS Pro or create local data sources, such as mobile geodatabases, shapefiles, GeoPackages, and tile caches, and sideload them onto your devices.

Services pattern

If your users need to access up-to-date information use the Services pattern to take your layer offline from ArcGIS Online or ArcGIS Enterprise services. This pattern allows you to build apps that can download feature data (also known as operational data) and tiled data directly to your device any time network connectivity is available.

To obtain offline feature data, l create and download a specific geographical area from a sync-enabled feature service into a
mobile geodatabase. If you edit this feature data, you can control whether the edits are uploaded, whether other users edits are downloaded, or both, when connectivity is restored. This synchronization process allows the app to maintain an up-to-date view of the feature data.

For
tiled data, you can create raster and vector tile caches from your own data or from Esri's export enabled basemaps, as follows:

You can export, download, and store these caches locally as packages and access them while your device is offline. You cannot edit this data, and if you require updates to the data, you must export and download them again.

Feature layers

You can view, identify, query, and edit features by taking specific features and feature layers offline with this API. Do this by exporting and downloading the features to geodatabase feature tables within a
mobile geodatabase. The feature service must be from ArcGIS for Server 10.2.2 or later, or from a service hosted in ArcGIS Online. The feature service must have sync enabled capabilities (allow disconnected editing with synchronization).

Generate geodatabase parameters

When you create a mobile geodatabase you must provide a set of parameters, described below, to define exactly which data is downloaded.

The geographical area of interest. You typically supply the area of interest as an extent (envelope, in other words) but point, line, and polygon (including multipart) geometries are also supported. This allows you to create more detailed areas of interest. Regardless of the geometry, any features that intersect with the supplied area of interest are extracted.

The spatial reference of the mobile geodatabase.

Individual layers can be managed using the
LayerOptions property:

Determine which layers are included in the mobile geodatabase.

Subset the features by providing an expression that filters features by attribute values, such as
ZONE = 'COM'.

The synchronization model controls how edits made to the mobile geodatabase are applied back to the feature service during synchronization. The model supported is defined by the data that was used to create the sync-enabled feature service. If the data is non-versioned, the synchronization model is per-layer. This is the most flexible model, allowing you to synchronize on a layer-by-layer basis, based on the layers you specify. If the data is versioned, the synchronization model is per-geodatabase. This synchronizes the entire geodatabase, including all layers and tables at once.

Specify whether to include feature attachments in the mobile geodatabase and whether they can be uploaded during synchronization.

Identify whether tables related to the layer are also included in the geodatabase.

You can obtain a default set of parameters (GenerateGeodatabaseParameters) using the CreateDefaultGenerateGeodatabaseParametersAsync method on the GeodatabaseSyncTask. If you provide the area of interest the default parameters will be generated taking into account the capabilities supported by the ArcGIS feature service. You can update these default parameter values before creating the geodatabase.

// Create a new GeodatabaseSyncTask to create a local version of feature service data.
Uri featureServiceUri = new Uri("http://sampleserver6.arcgisonline.com/arcgis/rest/services/Sync/SaveTheBaySync/FeatureServer");
GeodatabaseSyncTask gdbSyncTask = await GeodatabaseSyncTask.CreateAsync(featureServiceUri);
// Define an extent for the features to include.
Envelope dataExtent = MyMapView.GetCurrentViewpoint(ViewpointType.BoundingGeometry).TargetGeometry as Envelope;
// Get the default parameters for generating a geodatabase.
GenerateGeodatabaseParameters generateGdbParams = await gdbSyncTask.CreateDefaultGenerateGeodatabaseParametersAsync(dataExtent);
// Set the synchronization model to per layer.
generateGdbParams.SyncModel = SyncModel.Layer;
// Define the layers and features to include.
int marineLayerId = 0;
int birdsLayerId = 1;
string dolphinsOnlyWhereClause = "type = 11";
// Clear and re-create the layer options.
generateGdbParams.LayerOptions.Clear();
generateGdbParams.LayerOptions.Add(new GenerateLayerOption(marineLayerId, dolphinsOnlyWhereClause));
generateGdbParams.LayerOptions.Add(new GenerateLayerOption(birdsLayerId));
// Do not return attachments.
generateGdbParams.ReturnAttachments = false;
// Create the generate geodatabase job, pass in the parameters and an output path for the local geodatabase.
// ...

Create the geodatabase

Obtain a job to generate and download the geodatabase by passing the GenerateGeodatabaseParameters to the GenerateGeodatabase method on the GeodatabaseSyncTask. Run the job to generate and download the geodatabase to the device.

If you generate the geodatabase using these methods it will automatically register the geodatabase with its original service. This allows the data in the geodatabase to be synchronized with the original service. If you want to load this geodatabase onto a number of devices and allow those users to synchronize changes with the original service you must
register these individual geodatabases with the original service.

Note:

Tiled layers

Tiled layers typically provide geographical context to your maps as basemaps that display beneath your operational data. You can export and download tile caches directly to your device from any tiled data source that is export enabled. Esri provides a number of raster and vector basemaps for you to export and download:

Download raster tiled data

You can take raster tiled data offline by exporting and downloading the tiled data as a tile package (*.tpk) using the ExportTileCacheTask class. This task requires that the tiled map service supports the creation of an offline tile cache; specifically, it must enable the exportTiles operation. This can be found at the bottom of the service's HTML page.

Generate export tile cache parameters

Construct a default set of parameters (
ExportTileCacheParameters) by passing an area of interest along with the min and max scale thresholds to the
CreateDefaultExportTileCacheParametersAsync method on the
ExportTileCacheTask.

This method will return a set of parameters for the area of interest and will calculate the levels of detail (LODs) required to support the min and max scale for the service's tiling scheme. You can, if you wish, adjust these LOD levels or remove some before you download the cache.

Export and download the raster tile cache

Obtain an export and download job by passing the ExportTileCacheParameters to the ExportTileCacheJob method on the ExportTileCacheTask. Run the job to download the raster tile cache into a tile package that is placed in the download path on the device.

When creating an offline tile cache from a tiled service, consider the following:

The export tiles operation used to generate tile caches is only available with services hosted on ArcGIS 10.2.1 for Server or later.

Estimation of tile cache size is not available on ArcGIS Online hosted tiled services.

The time required to create a tile cache varies depending on the extent requested, the number of levels requested, the network connection speed, and so on. Use the
EstimateTileCacheSize
method on the
ExportTileCacheTask class which returns an
EstimateTileCacheTaskJob to get the approximate size of a tile cache for a specific set of parameters. Try generating a smaller tile cache to get an idea of how long caching will take when planning a large offline data capture event.

There is a limit to the number of tiles you can generate in a single request. When generating a tile cache from an ArcGIS Online basemap, there is a limit of 100,000 tiles per request. Read more on this in the ArcGIS REST API Documentation. Organizations that use their own ArcGIS Server to host an offline tile cache can configure the server's
maxExportTilesCount via the admin account to change the default limit of 100,000 tiles.

Download vector tiled data

You can take vector tiled data offline by exporting it from an ArcGIS Vector Tile Service and downloading it as a vector tile package (*.vtpk) using the
ExportVectorTilesTask class. The vector tile service used for this operation must support the creation of an offline vector tile cache; specifically, it must enable the
exportTiles operation. Vector tiles contain vector representations of data that can be restyled for different purposes such as day and night viewing. You can download default styling resources along with the vector tiles and custom style resources from ArcGIS Portal items that host Vector Tile Layers.

You have a number of workflows available to you depending on whether your vector tiled data has custom style resources, whether you wish to download many custom styles that you can apply to a number of tile caches, or whether you just want to obtain the default tile cache.

Instantiate the export vector tiles task

Instantiate the
ExportVectorTilesTask using a URL to the portal item that represents an ArcGIS Vector Tiled Layer. Load the task and upon completion check whether the vector tiles have custom style resources by checking the
HasStyleResources boolean value.

Note:

A URL to the portal item that represents an ArcGIS vector tiled layer. This gives you the ability to enable with the layer's custom styles. (Recommended approach)

A URL to the ArcGIS vector tile service itself. Use this option if you only want to display the service's default style.

Specify the export vector tiles task parameters

To obtain a default set of parameters call the
ExportVectorTileTask.CreateDefaultExportVectorTilesParametersAsync
method and provide an area of interest and a maximum scale. When you provide the maximum scale you must be aware that there won't be any tiles when the map is zoomed in beyond this scale. If you set the max scale to 0 the export will include all levels of detail in the service.

This method returns the set of default parameters,
ExportVectorTilesParameters, required to export the vector tiles to a vector tile package. The levels of detail (LODs) have been calculated to support the max scale that you specified.

Export the vector tiles

Obtain a job to generate and download a vector tile package and its default style resources by passing the
ExportVectorTilesParameters to the
ExportVectorTiles method on the
ExportVectorTilesTask. You must also provide a download path to store the vector tile package and it's default style resources.

Run the
exportVectorTileCacheJob to export and download the vector tile package (*.vtpk).

Note:

To obtain the vector tiles and the default style resources you must instantiate the
ExportTileCacheTask with a URL to the ArcGIS vector tile service.

Export the vector tiles with custom style resources

Obtain a job to generate and download a vector tile package containing tiles and associated style resources by passing the
ExportVectorTilesParameters to the
ExportVectorTiles method on the
ExportVectorTilesTask. The portal item's associated style resources will be downloaded and saved separately. You must also provide a download path to store the vector tile package and a separate download path for the style resources.

Run the job to export and download the vector tile package (*.vtpk) and the style resources to the device.

Note:

To obtain the vector tiles and its custom style resources you must instantiate the
ExportVectorTilesTask with a portal item that represents an ArcGIS Vector Tiled Layer

Desktop pattern

The desktop pattern allows you to distribute your GIS layers to a wide range of users who do not have access to online ArcGIS services. Using ArcGIS Pro and ArcMap you can create GIS files and packages and deliver them via email, FTP, the cloud, networks, thumb drives, and so on. The recipient just sideloads the files onto their device so that the ArcGIS Runtime apps can work offline without a network connection.

You could send these files to members of the public, staff in your organization or offline field workers. The desktop pattern is particularly suited for distributing GIS data to large numbers of people who do not need to synchronize their edits with the original data source.

Features stored in a GeoPackages provisioned by the OGC file format (.gpkg).

Features stored in the Shapefile format provided by the .shp file and its associated files (.dbf, .shx, etc).

Raster layer data stored in a raster dataset file or in a GeoPackage (.gpkg).

ArcGIS Pro and ArcMap provide a range of tools to create these GIS files and packages. The following sections demonstrate how you prepare these data files, add then to your ArcGIS Runtime app and create layers to display in your map.

Raster tiled layer

Raster tiled layers typically display pre-generated raster tiles as basemaps to give geographical context to other operational layers in a map. You can take a portion of this raster tiled data offline and store it within a single tile package (.tpk) file. You just need to specify the tiling scheme, the levels of detail, and the tile format using any of these tools:

In ArcMap, choose File > Share As > Tile Package to create a tile package file, as described in the Tile Package option help topic.

In ArcMap, choose Share as > ArcGIS Runtime Content to export the map's basemap layer to a tile package file (.tpk) that is output within the ArcGIS Runtime Content folder. This is described in the Creating ArcGIS Runtime content help topic which is available with ArcGIS 10.2.1 for Desktop or later.

Vector tiled layer

Vector tiled layers contain vector representations of data across a range of scales. Unlike raster tiles, they can adapt to the resolution of their display device as you zoom in and out. You can take an area of vector tiled data offline by exporting the vector tiles to a vector tile package file (.vtpk) using the Create Vector Tile Package tool in ArcGIS Pro. Be aware that ArcGIS Pro does not support custom styles and only packages the default styles into the vector tile package.

Note:

When you create a vector tile package it must be in the same spatial reference as the map in which it will be displayed.

To create a vector tiled layer from the vector tile package (.vtpk) instantiate an ArcGISVectorTiledLayer object with the vector tile package's file URL. The default style will be loaded directly from the vector tile package.

Feature layer

Feature layers allow you to display, select and query individual features and their attributes. If supported, you can also edit features, their attributes and their attachments. The desktop pattern allows you to work with features offline using cached features stored in an offline file, such as a geodatabase file (.geodatabase), a GeoPackage file (.gpkg), or a shapefile (.shp).

ArcGIS features

To generate a mobile geodatabase use the Share as > ArcGIS Runtime Content menu item as described in the ArcMap help topic Creating ArcGIS Runtime content. This is available with ArcGIS for Desktop 10.2.1 or later.

To create an offline feature layer from a mobile geodatabase (.geodatabase):

Instantiate the Geodatabase object with path to the geodatabase file.

Load the geodatabase and instantiate a FeatureTable from one of the geodatabase's feature tables.

Finally, create a FeatureLayer from the FeatureTable and add it as an operational layer to the map.

// Get the path to a local geodatabase.
string geodatabasePath = Path.Combine(Environment.ExpandEnvironmentVariables("%TEMP%"), "recreation.geodatabase");
// Open the geodatabase by providing the path.
Geodatabase localGdb = await Geodatabase.OpenAsync(geodatabasePath);
// Access one of the feature tables in the geodatabase using its name.
GeodatabaseFeatureTable trailheadsTable = localGdb.GeodatabaseFeatureTable("Trailheads");
// Create a feature layer from the table and add it to the map's operational layers.
FeatureLayer trailheadsLayer = new FeatureLayer(trailheadsTable);
MyMapView.Map.OperationalLayers.Add(trailheadsLayer);

GeoPackage

GeoPackage is an open, standards-based, platform-independent, portable, self-describing, compact format for transferring geospatial information. It uses a single SQLite file (.gpkg) that conforms to the OGC GeoPackage Standard. You can create a GeoPackage file (.gpkg) from your own data using the create a SQLite Database tool in ArcGIS Pro.

To display features stored in a GeoPackage file you must:

Instantiate the GeoPackage with the .gpkg file path.

Load the GeoPackage and then examine its list of GeoPackageFeatureTables.

Create a FeatureLayer from one of the GeoPackageFeatureTables and add it as an operational layer to the map.

// Get the path to a local geopackage.
string geopackagePath = Path.Combine(Environment.ExpandEnvironmentVariables("%TEMP%"), "trails.gpkg");
// Open the geopackage by providing the path.
GeoPackage trailsGpkg = await GeoPackage.OpenAsync(geopackagePath);
// Iterate feature tables in the package to find one by name.
foreach (GeoPackageFeatureTable table in trailsGpkg.GeoPackageFeatureTables)
{
if (table.TableName.ToLower() == "trailheads")
{
// Create a feature layer from the table and add it to the map's operational layers.
FeatureLayer trailheadsLayer = new FeatureLayer(table);
MyMapView.Map.OperationalLayers.Add(trailheadsLayer);
}
}

Shapefiles

To create a feature layer from a shapefile (.shp):

Instantiate the ShapefileFeatureTable with the path to the shapefile. This path must point to the .shp file and the associated .shx and .dbf files must be present at the same location.

Create a FeatureLayer from the ShapefileFeatureTable and add it as an operational layer to the map.

// Get the path to a local shapefile.
string shapefilePath = Path.Combine(Environment.ExpandEnvironmentVariables("%TEMP%"), "trails.shp");
// Create a shapefile feature table using the path.
ShapefileFeatureTable trailsFeatureTable = await ShapefileFeatureTable.OpenAsync(shapefilePath);
// Create a feature layer from the table and add it to the map's operational layers.
FeatureLayer trailsLayer = new FeatureLayer(trailsFeatureTable);
MyMapView.Map.OperationalLayers.Add(trailsLayer);

Raster layer

Raster datasets consist of a matrix of cells where an individual cell contains a value representing information. Each cell's value can be discrete, in the case of a soil map, or continuous, such as air temperature. You can identify and query these cell values and define renderers to display the data. In addition, raster data can also comprise satellite or aerial images and photographs for visualizing an area. This SDK supports several raster formats. You can sideload these onto your device and add the raster dataset to your map using the RasterLayer class.